STAINLESS STEEL NORD-LOCK WASHERS ? GLUED PAIRS

Nord-Lock Washers – Glued Pairs — Nord-Lock washers work on a wedge-lock principle rather than friction: two washers with radial cams machined into their mating faces are installed as a pair, and any tendency for the joint to rotate loose draws the cam faces further up their inclines, increasing bolt tension rather than releasing it. That mechanism makes them a common specification wherever a joint is exposed to genuine vibration or dynamic loading and the consequence of it working loose is severe — structural bolting, heavy vehicle and rail applications, wind turbine assemblies, and machinery subject to constant cyclic vibration, where a friction-based lock washer's resistance can eventually be overcome. For a joint that sees only mild, occasional vibration, a standard spring or serrated lock washer is usually adequate and considerably cheaper; the wedge-lock design earns its higher cost specifically where the joint absolutely cannot be allowed to loosen, or where the cost of inspecting and re-torquing a failed joint in service is high. Because the locking action comes from a patented cam-face geometry rather than a dimension or feature set out in a published DIN or ISO standard, the washer's performance claims and installation requirements are best confirmed against the manufacturer's own technical documentation for a critical application, rather than assumed from general washer standards. The pair is supplied glued together purely to keep the two cam faces correctly aligned during handling and installation — the adhesive plays no role in the locking function itself, which is entirely mechanical. Sizing follows the same principle as any flat washer: match the bore to the bolt diameter, and remember that a pair adds twice the stack height of a single flat washer, which should be allowed for when calculating grip length and thread engagement on the fastener. PTS stocks the standard metric size range in stainless steel to match its wider washer offering.

FAQs
Does the glue play any role in the locking function?
No. The adhesive only holds the pair together correctly aligned for handling and installation; the locking action is generated entirely by the mechanical cam-face geometry once the washers are compressed in the joint.

Can Nord-Lock washers be reused?
As with any washer relying on cam-face geometry, Nord-Lock washers should be inspected before reuse — provided the cam faces show no visible wear or damage, they can generally be refitted, but a fresh pair is recommended for a critical or safety-related joint.

Does using a pair change the grip length or thread engagement I need to allow for?
Yes — a glued pair adds roughly twice the stack height of a single flat washer, so this should be factored into grip length and thread engagement calculations when specifying bolt length for the joint.